Technical Field
The present invention relates to an inkjet printing method using an oil-based ink containing a dye lake pigment and an inkjet printer used in the printing method.
Related Art
An ink used in inkjet printing is roughly divided into an aqueous ink and a non-aqueous ink, and a non-aqueous ink is classified into a solvent-based ink containing a volatile solvent as a main solvent and an oil-based ink containing a non-volatile solvent as a main solvent. The oil-based ink does not cause curl of printed matter, and a solvent is less likely to volatilize than from aqueous inks and solvent-based inks, thus is excellent in maintainability such that clogging of the ink nozzle is unlikely to occur, and cleaning counts of the ink nozzle can be reduced, and has little burden on printing system, therefore, the oil-based ink is suitable for high-speed printing, especially, a high-speed inkjet printing of a line head system. On the other hand, the coloring material used in the oil-based ink includes dyes and pigments, and recently a pigment is increasingly used, from the viewpoint of environment resistance (preservability, water resistance, etc.) of printed matter (JP 2005-350493 A).
Incidentally, a phenomenon in which a printing image is seen through from the back side of the printed matter is referred to as “strike through”. In the oil-based ink, a solvent does not volatilize and remains inside the recording medium for a long period, thus the coloring material having high affinity with the solvent is drawn into inside the recording medium with permeation of a solvent, and consequently, strike through tends to deteriorate. Also, when a dye is used as the coloring material, the dye dissolves in the solvent and sinks inside the recording medium together with the solvent, thus strike through further deteriorates.